nx_find.nx

nx_find.nx -- S5 stone of NISHI_SHELL_REPLACEMENT_ROADMAP.md. Canonical: this is the substrate-wide canonical file-tree walk + filter primitive per [[feedback-bits-up-shell-replace-linux- brother-tools]]. Composes nx_dir + nx_string_ops + nx_grep. Replaces the bash `find` / `ls | xargs grep` patterns scattered across substrate audit scripts. S6 will add recursive walks + gitignore-aware exclusions (fd 2017 style); this S5 first stone ships the per-level filter primitives that the recursive walker composes. API (all pure-function over caller-provided NxDirRow arrays; no syscalls in the LOGIC layer; caller composes nx_dir_list to populate rows then runs filters): nx_find_filter_suffix(rows, n_rows, suffix, n_suffix, out_flags) -> i64 For each row, sets out_flags[i] = 1 iff name ends with suffix. Returns count of kept rows. nx_find_filter_prefix(rows, n_rows, prefix, n_prefix, out_flags) -> i64 For each row, sets out_flags[i] = 1 iff name starts with prefix. Returns count of kept rows. nx_find_filter_regular_files(rows, n_rows, out_flags) -> i64 For each row, sets out_flags[i] = 1 iff dtype == NX_DT_REG. Returns count of kept rows. nx_find_filter_skip_dotlike(rows, n_rows, out_flags) -> i64 For each row, sets out_flags[i] = 1 iff NOT is_dotlike. nx_find_intersect(a, b, n, out_flags) -> i64 out_flags[i] = a[i] AND b[i]. Composes multiple filters. nx_find_count_kept(flags, n) -> i64 Sum of 1s in flags array. nx_find_nth_kept_index(flags, n, k) -> i64 Returns the index of the k-th kept row (0-based), or -1 if k exceeds count. Lets the caller iterate kept rows without allocating a separate index list.